Since prehistoric times, man has been able to capture and depict objects only in the form of static two-dimensional images. Only a century ago did it become possible to capture the motion of an object in the form of a series of single frames and to play them back as an animation. In echocardiography, motion was first represented in M-mode images, in which one axis of the display showed the echoes of a single scanline while a second axis coded time. The advent of two-dimensional echocardiographic imaging led to the current method of representing real time myocardial motion as video sequences. This development improved the understanding of cardiac structure in vivo and added new insights into cardiac function. However, viewing cardiac motion in a compact display becomes more cumbersome with 2D- compared to M-mode echocardiography.
Currently, echocardiograms are stored primarily on videotapes, but digital storage media are being used more frequently for echocardiograms as well as for magnetic resonance and other medical imaging techniques. However, the search and review of studies on videotapes is time consuming and impractical, and both video and digital storage media require expensive and heavy equipment. Simple printing of single echocardiographic frames (similar to what is routinely done in radiology) is not practical because motion, a principal information content of heart imaging, is lost if a frame is printed. No methods exist to display, in a printable format, a moving heart in two-dimensional or three-dimensional images. At the current time, echocardiography machine manufacturers are developing hardware and software that allow both the digital image acquisition and the presentation of echocardiographic studies on portable computers. Holography has been used to display static 3-dimensional images of the pelvis, the spine and the brain, by using computer tomography, magnetic resonance imaging and sonographic techniques to acquire image information. One description of holographic imaging of the heart was likewise limited to the representation of static images of a explanted animal heart.
In contrast to the above described applications in biomedicine, dynamic datasets containing object motion, mainly of the heart, as acquired by ultrasound, computer tomography or magnetic resonance tomography, contain a significantly higher amount of data, posing additional problems for representation in an understandable manner; application of holography to dynamic datasets of the beating heart has not been reported.